The present invention relates to a method of manufacturing a battery can-forming plate and the battery can-forming plate manufactured by the method.
Batteries are used as a power source of various kinds of cordless equipments such as personal lap-top computers, cellular telephones, and the like which are widely used in recent years. The space occupied by the batteries is very large. In order to make the portable equipments compact and light, it is necessary to provide them with batteries which are compact and light and yet have a high performance. To this end, battery cans are required to have high capacities. But the outer shapes of the battery cans are specified by the international standard. In order to allow the battery cans to have high capacity, it is necessary to make the thickness thereof small.
A battery can-forming plate is hitherto manufactured by hot-rolling casted slab, then by cold-rolling a resulting hot-rolled steel plate to a required thickness, and then, by plating the cold-rolled steel plate with nickel or other metals.
In another conventional method, after the cold-rolled steel plate is rolled to 1%-3% which is short of a required thickness of a final product, plated and then annealed. Then, the steel plate is rolled to 1%-3% by a skin pass roller to allow the final product to have the required thickness.
The annealing after the plating is performed and the skin pass rolling are intended to form a diffusion layer between iron of the steel plate and the plated metal layer.
In the conventional manufacturing method, because a tin plate (for example, as thin as 0.2 mm-0.25 mm) obtained after the cold rolling is plated, electric resistance is high and thus it is very difficult to make current (current density A/dm.sup.2) high in the plating operation. Therefore, in order to increase productivity, it is necessary to use an electrolytic tank as long as tens of meters to hundreds of meters. In this case, much chemicals are required to plate the cold-rolled steel plate, electric equipments are large-sized, and much electric power is consumed. Moreover, because the cold-rolled steel plate is thin, the length thereof per unit weight is great. Thus, the productivity of the conventional manufacturing method is poor.